The present invention relates to an apparatus for conveying and positioning circular sheet materials, the apparatus being incorporated in a processing apparatus.
An apparatus of this kind has been well known, for example, in case that the material to be processed is a substrate for integrated circuits, i.e. silicon wafer, the wafer which is round or at least approximately circular is to a predetermined position of a processing apparatus, where it is held, or while being rotated, to be subjected to required processings. Such apparatus is so-called vacuum suction type, which enables the wafer to be held by vacuum suction and to be rotated at about several 100 rpm. However, in this kind of apparatus, there have been such disadvantages as follows. That is, first, a conventional apparatus would require the complexity of its construction, because a supporting shaft which supports a base on which a wafer is held and rotates it together with the wafer set thereon is also functioned as a suction pipe for holding the wafer by vacuum suction therethrough. Second, when a processing solution is sprayed onto the wafer, the processing solution supplied on the wafer surface, which has in general corroding functions, would be apt to flow into the suction pipe which corresponds to the supporting shaft, or up to a vaccum pump, whereby the processing apparatus itself tends to be subjected to damages, because of its inherent construction as mentioned in the first disadvantage.